Process for the stabilization of chlorinated hydrocarbons



United States Patent PROCESS FOR THE STABILIZATION OF CHLORINATED HYDROCARBONS Nestor Daras, Ixelles-Brussels, Belgium, assignor to S0!- vay 8: Cie., Brussels, Belgium, a Belgian company No Drawing. Filed Dec. 9, 1958, Ser. No. 779,077 'Claims priority, application Belgium Dec. 19, 1957 6 Claims. (Cl. 260-6525) The present invention relates to a process for the stabilisation of chlorinated hydrocarbons, particularly trichlorethylene and perchlorethylene, with a view of preventing the decomposition of these products and the of acid during storage or in V for improving the resistance to decomposition of chlori- Patented Apr.- 4, 1961 particularly with as tertiary or normal butyl alcohol, tertiary amyl alcohol,

ethylenic or acetylenic alcohols such as allyl alcohol methylbutynol, diol others such as methylcellosolveor monomethyl ether of ethylene glycol and the like.

The stabilising action of the various compounds used nated hydrocarbons is demonstrated by an accelerated laboratory test which is carried out as follows: H I

150 cc. of, for example, trichlorethylene and a test piece of aluminium are placed in a 300 cc. flask of a trichlorethylene turns black and posed to add to these chlorinated hydrocarbons small 7 quantities of various products such as alcohols, mineral and organic basic products, phenols, epoxy compounds etc.

However effective these stahi'lisers may be for preventing the oxidation of chlorinated hydrocarbons, they are, in general incapable of preventing a rapid decomposition of these chlorinated hydrocarbons in the course of their use for the de-greasing of light metals, especially aluminium and its alloys.

The addition of one stabilising compound alone is in general, insuflicient for preventing the decompositions of chlorinated hydrocarbons, particularly if they are used for the de-greasing of metals. 7

Moreover, the addition of several stabilising compounds does not always lead to the desired result, either because of their incompatibility, or because of the fact that too large quantities of products are necessary to ensure a good stabilisation.

it has already been proposed to combine the stabilising action of epoxy compounds such as epichlorhydrin with that of amines. A synergistic action would thus permit to reduce considerably the quantity of amines necessary for a good stabilisation, but when the chlorinated hydroc-arbons are used for the de-greasing of light metals, the combined action of epichlorhydrin and certain amines such as triethylamine, cyclohexylamine, methoxypropylamine, dimet-hoxypropylamine, piperidine and aniline has proved, according to the test described below, to be inferior to that of epichlorhydrin alone.

It has also been proposed (U.S. patent application No. 771,754) to combine the stabilising action of epichlorhydrin with that of phenols, but important synergistic eliects have hitherto been obtained only with phenol.

The present invention relates to a new combination of stabilising reagents leading to particularly valuable results.

According to the invention, chlorinated hydrocarbons, particularly trichlorethylene and perchlorethy-lene, are stabilised by adding small quantities of an alcohol and of a phenol.

All phenols the physical properties of which are compatible with the normal use of chlorinated hydrocarbons may be employed according to the process of the inven- Soxhlet extracting apparatus fitted with a 65 ccsextractorc The flask is electrically heated and the trichlorethylene is rapidly brought to the boil under reflux at a, constant-- rate, while an oxygen stream is passed through the ap-" paratus which is illuminated by a'fiuorescent lamp of the Blue actiuic type. During the wholefduration of the test, the rate of evolution of acid vapours at the outlet of the apparatus is measured. This rate which is very' low at the start becomes suddenly very high, whilst the is transformed intoa black tarry :nass. I

The resistance of trichlorethylene to the test is measured by time, expressed in hours, counted from the start of the test, ie as soon as the sample is brought to the boil, to the instant where the evolution of acid sud- Table 1 Resistance Test No. Stabilizing substances, mg./l. in the ac- V celerated test, hrs.v

1 Nil 22 normal butyl alcohol (1,500). 28 tertiary butyl alcohol'(1,500) F 37 tertiary amyl alcohol (1,500). 33 methylccllosolve (1,500)-.- 35 allyl alcohol (1,500)... 58 methylbutynol (1,500 40 phenol .4 64 phenol (200)....- 95 0 cresol (200) thyrnol (100) 35 phenol (l00)normal butyl alcohol (1,500). 122 phenol (100)tertiary butyl alcohol (1,500) 137 phenol (100)tertiary amyl alcohol (1,500) 155 phenol (200)-tertiary amyl alcohol (1,500).- 280 o. cresol (200)tertiary amyl alcohol (1,500)-.. 390 thymol (100)tertiary amyl alcohol (1,500)... 92 phenol (100)al1yl alcohol (1,500) phenol (l00)methylcellosolve (1,500) 147 phenol (l00):nethylbutynol (1,500). 144 phenol (200)methylbutynol (1,500) 220 The tests 12 to 21 show that by combining the stabilising action of phenols with that of alcohols, there is obtained a resistance of chlorinated hydrocarbons to decomposition which is superior to the sum of results obtainable by using the compounds separately.

The synergistic effect is particularly marked when tertiary alcohols are combined with phenols.

This efifect increases with the phenol content, but it is already very substantial at phenol concentrations of 100 to 200 mg./litre.

It is possible to add to the combination of substances which form the object of the invention, other compounds T known for their stabilising action. The resistance to decomposition is particularly increased by adding pyrrole,

3 pyrrole derivatives or aniline, as can be seen from the tests listed in the following Table 2.

Table 2 Resistance Test; No. Stabilizing substances, mg./l. in acceleratcd test, hrs.

22 pyrrole (100) 84 23 pyrrole (200) 164 24 pyrrolc (100)+phcnol (100) 158 25 phenol (100)-l-tertiary amyl alcohol (1,500)+ pyrrolc (100) 269 26 phenol (200)-l-tcrtiary amyl alcohol (1,500)+ 500 pyrrole (200). tertiary amyl alcohol (1,500)+pyrrolc (200)...- 206 ani ine (200) 2 phenol (100)+aniline (100) 82 tertiary amyl alcohol (1.500l-l-anilinc (200) 53 phenol (l)+tertiary amyl alcohol (1,500)+ 201 aniline (100). phenol (200)+tcrtiary amyl alcohol (1,500)+ 500 aniline (200).

Compared with the tests 14-43 of Table l, the tests 2526 and 3l32 show that pyrrole and aniline are advantageously combined with binary alcohol-phenol stabilisers and noticeably increase the synergistic effect. In contrast to this, the same compounds combined with an alcohol alone or a phenol alone lead only to additive results.

The resistances of more than 500 hours which have been found are extraordinary when taking into account that during the accelerated test the boiling chlorinated hydrocarbon is simultaneously subjected to the action of oxygen and light in the presence of aluminium.

The quantitiesof stabilising matters to be used according to the process of the invention may generally be comprised between 0.05 and 0.5 g./ litre of phenol and between 0.5 to 10 g./litre of alcohol. The most advantageous proportions seem to be 0.1 to 0.25 g. of phenol and l to 3 g. of alcohol per litre of hydrocarbon to be stabilised.

Small quantities of pyrrole derivatives and/ or of aniline appreciably increase the resistance of chlorinated hydrocarbon to decomposition. The latter compounds are advantageously added at a ratio of 0.05 to 0.5 g./litre, but considerably smaller proportions are already effective.

Although the stabilising compounds based on phenols and/or alcohols are particularly effective in the stabilisation of trichlorethylene, one of the chlorinated hydrocarbons which are most sensitive to decomposition, they may also be used for the stabilisation of perchlorethylene 4 and of other chlorinated solvents such as carbon tetrachloride, dichlorethane, trichlorethane and the like.

I claim:

1. A process for the stabilization of a chlorinated hydrocarbon solvent to inhibit its decomposition and the simultaneous formation of acids, which comprises adding to said solvent 0.05 to 0.5 g. of a phenol selected from the group consisting of phenol and the cresols, and 0.5 to 10 g. of tertiary amyl alcohol per liter of said chlorinated hydrocarbon solvent.

2. A process for the stabilization of a chlorinated hydrocarbon solvent to inhibit its decomposition and the simultaneous formation of acids, which comprises adding to said solvent 0.05 to 0.5 g. of a phenol selected from the group consisting of phenol and the cresols, 0.5 to

10 g. of a tertiary amyl alcohol, and 0.05 to 0.5 g. of a compound selected from the group consisting of pyrrole and aniline per liter of said chlorinated hydrocarbon solvent.

3. A process for the stabilization of trichlorethylene to inhibit its decomposition and the simultaneous formation of acids, which comprises adding to said trichlorethylene 0.05 to 0.5 g. of a phenol selected from the group consisting of phenol and the cresols, and 0.5 to 10 g. of tertiary amyl alcohol per liter of said trichlorethylene.

4. A composition of matter comprising a chlorinated hydrocarbon solvent, 0.05 to 0.5 g. of a phenol selected from the group consisting of phenol and the cresols, and 0.5 to 10 g. of tertiary amyl alcohol per liter of said chlorinated hydrocarbon solvent.

5. A composition of matter comprising trichlorethylene, 0.05 to 0.5 g. of a phenol selected from the group consisting of phenol and the cresols, and 0.5 to 10 g. of tertiary amyl alcohol per liter of said trichlorethylene.

6. A composition of matter comprising trichlorethylene, 0.05 to 0.5 g. of a phenol selected from the group consisting of phenol and the cresols, 0.5 to 10 g. of tertiary amyl alcohol, and 0.05 to 0.5 g. of a compound selected from the group consisting of pyrrole and aniline per liter of said trichlorethylene.

References Cited in the file of this patent UNITED STATES PATENTS 2,371,644 Petering et al. Mar. 20, 1945 2,797,250 Copelin June 25, 1957 2,803,676 Willis et al Aug. 20, 1957 2,911,449 Herman et al. Nov. 3, 1959 FOREIGN PATENTS 787,726 Great Britain Dec. 11, 1957 

1. A PROCESS FOR THE STABILIZATION OF A CHLORINATED HYDROCARBON SOLVENT TO INHIBIT ITS DECOMPOSITION AND THE SIMULTANEOUS FORMATION OF ACIDS, WHICH COMPRISES ADDING TO SAID SOLVENT 0.05 TO 0.5 G. OF A PHENOL SELECTED FROM THE GROUP CONSISTING OF PHENOL AND THE CRESOLS, AND 0.5 TO 10 G. OF TERTIARY AMYL ALCOHOL PER LITER OF SAID CHLORINATED HYDROCARBON SOLVENT. 